ITK  5.2.0
Insight Toolkit
Examples/Filtering/ResampleImageFilter8.cxx
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* Copyright NumFOCUS
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* Licensed under the Apache License, Version 2.0 (the "License");
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// Software Guide : BeginLatex
//
// The following example illustrates how to use the
// \doxygen{WindowedSincInterpolateImageFunction} for resampling an image.
// This interpolator is in theory the best possible interpolator for
// reconstructing the continous values of a discrete image. In the spectral
// domain, this interpolator is performing the task of masking the central
// part of the spectrum of the sampled image, that in principle corresponds
// to the spectrumn of the continuous image before it was sampled into a
// discrete one. In this particular case an \doxygen{AffineTransform} is used
// to map the input space into the output space.
//
// \index{itk::AffineTransform!resampling}
//
// Software Guide : EndLatex
#include "itkImage.h"
// Software Guide : BeginLatex
//
// The header of the affine transform is included below.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
// Software Guide : EndCodeSnippet
int
main(int argc, char * argv[])
{
if (argc < 4)
{
std::cerr << "Usage: " << std::endl;
std::cerr << argv[0] << " inputImageFile outputImageFile degrees"
<< std::endl;
return EXIT_FAILURE;
}
constexpr unsigned int Dimension = 2;
using InputPixelType = unsigned char;
using OutputPixelType = unsigned char;
using InputImageType = itk::Image<InputPixelType, Dimension>;
using OutputImageType = itk::Image<OutputPixelType, Dimension>;
ReaderType::Pointer reader = ReaderType::New();
WriterType::Pointer writer = WriterType::New();
reader->SetFileName(argv[1]);
writer->SetFileName(argv[2]);
const double angleInDegrees = std::stod(argv[3]);
// Software Guide : BeginLatex
//
// The Resampling filter is instantiated and created just like in previous
// examples. The Transform is instantiated and connected to the resampling
// filter.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using FilterType =
FilterType::Pointer filter = FilterType::New();
TransformType::Pointer transform = TransformType::New();
filter->SetTransform(transform);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The salient feature of this example is the use of the
// \doxygen{WindowedSincInterpolateImageFunction}, which uses a truncated
// \emph{sinc} function in order to interpolate the resampled image.
//
// There is a close relationship between operations performed in the
// spatial domain and those applied in the spectral doman. For example, the
// action of truncating the \emph{sinc} function with a box function in the
// spatial domain will correspond to convolving its spectrum with the
// spectrum of a box function. Since the box function spectrum has an
// infinite support on the spectral domain, the result of the convolution
// will also have an infinite support on the spectral domain. Due to this
// effects, it is desirable to truncate the \emph{sinc} function by using a
// window that has a limited spectral support. Many different windows have
// been developed to this end in the domain of image processing. Among the
// most commonly used we have the \textbf{Hamming} window. We use here a
// Hamming window in order to define the truncation of the sinc function.
// The window is instantiated and its type is used in the instantiation of
// the WindowedSinc interpolator. The size of the window is one of the
// critical parameters of this class. The size must be decided at
// compilation time by using a \code{const integer} or an \code{enum}.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
using BoundaryConditionType =
constexpr unsigned int WindowRadius = 5;
using WindowFunctionType =
using InterpolatorType =
WindowRadius,
WindowFunctionType,
BoundaryConditionType,
double>;
InterpolatorType::Pointer interpolator = InterpolatorType::New();
filter->SetInterpolator(interpolator);
filter->SetDefaultPixelValue(100);
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The parameters of the output image are taken from the input image.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
reader->Update();
const InputImageType::SpacingType & spacing =
reader->GetOutput()->GetSpacing();
const InputImageType::PointType & origin = reader->GetOutput()->GetOrigin();
const InputImageType::DirectionType & direction =
reader->GetOutput()->GetDirection();
reader->GetOutput()->GetLargestPossibleRegion().GetSize();
filter->SetOutputOrigin(origin);
filter->SetOutputSpacing(spacing);
filter->SetOutputDirection(direction);
filter->SetSize(size);
// Software Guide : EndCodeSnippet
filter->SetInput(reader->GetOutput());
writer->SetInput(filter->GetOutput());
TransformType::OutputVectorType translation1;
const double imageCenterX = origin[0] + spacing[0] * size[0] / 2.0;
const double imageCenterY = origin[1] + spacing[1] * size[1] / 2.0;
translation1[0] = -imageCenterX;
translation1[1] = -imageCenterY;
transform->Translate(translation1);
std::cout << "imageCenterX = " << imageCenterX << std::endl;
std::cout << "imageCenterY = " << imageCenterY << std::endl;
const double degreesToRadians = std::atan(1.0) / 45.0;
const double angle = angleInDegrees * degreesToRadians;
transform->Rotate2D(-angle, false);
TransformType::OutputVectorType translation2;
translation2[0] = imageCenterX;
translation2[1] = imageCenterY;
transform->Translate(translation2, false);
// Software Guide : BeginLatex
//
// The output of the resampling filter is connected to a writer and the
// execution of the pipeline is triggered by a writer update.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
try
{
writer->Update();
}
catch (const itk::ExceptionObject & excep)
{
std::cerr << "Exception catched !" << std::endl;
std::cerr << excep << std::endl;
}
// Software Guide : EndCodeSnippet
return EXIT_SUCCESS;
}
itk::GTest::TypedefsAndConstructors::Dimension2::DirectionType
ImageBaseType::DirectionType DirectionType
Definition: itkGTestTypedefsAndConstructors.h:52
itk::GTest::TypedefsAndConstructors::Dimension2::PointType
ImageBaseType::PointType PointType
Definition: itkGTestTypedefsAndConstructors.h:51
itkImageFileReader.h
itk::GTest::TypedefsAndConstructors::Dimension2::SizeType
ImageBaseType::SizeType SizeType
Definition: itkGTestTypedefsAndConstructors.h:49
itkImage.h
itkAffineTransform.h
itk::AffineTransform
Definition: itkAffineTransform.h:101
itkConstantBoundaryCondition.h
itk::ImageFileReader
Data source that reads image data from a single file.
Definition: itkImageFileReader.h:75
itk::ConstantBoundaryCondition< InputImageType >
itk::ImageFileWriter
Writes image data to a single file.
Definition: itkImageFileWriter.h:87
itkImageFileWriter.h
itk::WindowedSincInterpolateImageFunction
Use the windowed sinc function to interpolate.
Definition: itkWindowedSincInterpolateImageFunction.h:270
itkWindowedSincInterpolateImageFunction.h
itk::ResampleImageFilter
Resample an image via a coordinate transform.
Definition: itkResampleImageFilter.h:90
itk::Image
Templated n-dimensional image class.
Definition: itkImage.h:86
itkResampleImageFilter.h
itk::GTest::TypedefsAndConstructors::Dimension2::Dimension
constexpr unsigned int Dimension
Definition: itkGTestTypedefsAndConstructors.h:44
itk::Function::HammingWindowFunction
Window function for sinc interpolation.
Definition: itkWindowedSincInterpolateImageFunction.h:60
itk::Size::GetSize
const SizeValueType * GetSize() const
Definition: itkSize.h:169